noun, plural pe·num·brae [pi-nuhm-bree] /pɪˈnʌm bri/, pe·num·bras.
a. the partial or imperfect shadow outside the complete shadow of an opaque body, as a planet, where the light from the source of illumination is only partly cut off. Compare umbra(def 3a).
b. the grayish marginal portion of a sunspot. Compare umbra(def 3b).
2. a shadowy, indefinite, or marginal area.
pe·num·bral , pe·num·brous , adjective
Related Words for penumbra
shadow, dark, gloom, obscurity, shade, darkness, dusk, screen, cover, shadiness, umbrage, blackness, coolness, penumbra, umbra, semidarkness, gloominess, adumbration, shelter, protection
See more synonyms on Thesaurus.com
Origin: 1660–70; < New Latin, equivalent to Latin paen- pen- + umbra shade
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